Coaxial connector

ABSTRACT

A coaxial connector has solid conductive sleeves surrounding both the inner and outer conductor contacts to reduce RF leakage and degradation caused by mechanical discontinuities. The connector has all contacts in one half of the connector and very low insertion forces are sufficient to achieve good electrical contact.

:1; States Patent lnventor Roger J. Colardeau Florham Park, NJ. Appl. No. 881,008 Filed Dec. 1, 1969 Patented Nov. 2, 1971 Assignee Bell Telephone Laboratories, lncorporated Murray Hill, NJ.

COAXllAL CONNECTOR 2 Claims, 5 Drawing Figs.

US. Cl 339/177 E, 339/262 RR, 339/278 C Int. Cl. H0lr 17/06, 1101: 1 1/22 Field 01 Search 339/60 C,

64,89 C, 90 C, 91 P, 94 C, 126.1, 177 R, 177 E, 259 R, 275 R, 275 B, 275 C, 275 T, 278 C, 278 M, 262

[56] References Cited UNITED STATES PATENTS 2,379,942 7/1945 Webber.... 339/60 2,762,025 9/1956 Melcher 339/177 X 3,022,482 2/1962 Waterfield et a1. 339/89 3,260,907 7/1966 Weller et a1. 317/261 3,391,380 7/1968 Robinson etal. 339/143 FOREIGN PATENTS 1,133,380 11/1968 Great Britain 339/177 Primary Examiner-Stephen J. N ovosad Attorneys-R. J. Guenther and Edwin B Cave ABSTRACT: A coaxial connector has solid conductive sleeves surrounding both the inner and] outer conductor contacts to reduce RF leakage and degradation caused by mechanical discontinuities. The connector has all contacts in one half of the connector and very low insertion forces are sufficient to achieve good electrical contact.

PATENTEU wuvz ISYI $617,990

ATTOR Y comm. comsae'roa GOVERNMENT CONTRACT BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to electrical connectors, and, more particularly, to a low leakage coaxial connector having all spring contacts in one half of the connector.

2. Description of the Prior Art Most presently used precision coaxial connectors make use of butt joints in the outer conductor and rather elaborate contact devices in the inner conductor. Low tolerance fits between the mating parts of these conductors are usually required to achieve good electrical contact and high performance. Additionally, the connectors utilize relatively large amounts of expensive materials. Thus, the connectors are expensive. Further, the butt joint interface requires substantial closure forces for the connectors. The required forces are generally supplied by fine pitch, threaded, coupling devices. The use of these connectors, in addition to low tolerance fits, requires accessibility in order to achieve a connection. Therefore, the connectors usually cannot be used in a multiport-tomultiport configuration which is often encountered in highdensity packaging.

Many of the presently used common connectors present discontinuities, such as mechanical discontinuities in the surfaces of the outer and inner conductors, to the propagated signal thereby causing a degradation of electrical performance. Additionally, most of these connectors have substantial RF leakage at the connector joint, and rely on the coupling device to provide additional shielding.

Accordingly, it is an object of this invention to improve coaxial connectors to permit their use in multiport-to-multiport configurations.

Another object is to improve the design of coaxial connectors by providing more effective RF shielding and by eliminating degradations caused by mechanical discontinuities within the connector.

A further object is to improve the design of coaxial connectors to permit the manufacture of a more economical connector while simultaneously providing improved performance.

SUMMARY OF THE INVENTION The foregoing objects and others are achieved in accordance with the principles of the invention by a coaxial connector which contains all spring contacts in the female half of the connector. The spring contacts of the center conductor are surrounded by a conductive resilient silicone adhesive and the resulting structure is enclosed in a solid sleeve. The tapered end of the center conductor of the male half of the connector is inserted into the spring contacts and the center conductor also forms a butt joint with the end of the solid sleeve, thereby presenting a continuous surface to the propagated wave. The spring contacts of the outer conductor are mounted in a recessed portion of the interior surface of the outer female sleeve or barrel and thus contact the solid male barrel around its entire exterior surface upon insertion. The end of the male barrel also forms a butt joint with the rear of the recessed portion. Therefore, a continuous surface is presented to the propagated wave by the outer conductor, and the critical dimensions of the connector are not subject to change because of connector wear. Distortion of the spring contacts also has no effect on the critical electrical dimensions of the connector. The connector is interchangeable with present designs as typified by the "N" series of Military Specification MIL C 390l2A and it utilizes a minimum of expensive materials.

The invention will be more fully comprehended from the following detailed description and accompanying drawing in which:

FIG. l is a cutaway, perspective view of the connector of this invention;

FIG. 2 is a sectional view of the direction 2-2 of FiG. 1;

FIG. 3 is a perspective view of the outer spring contact of the connector shown in FIG. 2; and

FIGS. d and h are perspective views of other spring contacts which may be substituted for the outer spring contact shown in FIG. 3.

connector talten along DETAILED DESCRIPTION As shown in FIG. I, the coaxial connector 1101 comprises two sections or halves which are the female or receptacle half 6 and the male or plug half 8 which connect cable sections 56 and 58. These two sections combine to form the connector having an inner conductor 12 and a coaxial outer conductor 10. The male half 8 of the connector Hill has only solid or rigid conductors whereas the female half 6 includes spring contacts on both the inner and outer conductors to provide the required flexibility to insure good electrical contact without precision control of the connector parts.

As shown more fully in FIG. 2, the inner contact of the female half 6 of the connector 101 includes a plurality of contacts 24 which surround the tapered end 205 of the solid center conductor of the male half 8 and make good electrical contact therewith. The contacts 24 may appropriately be longitudinal slices of a sleeve or tube of conductive material. The separation of the edges of the contacts 2A, i.e., the interstice 23, is somewhat exaggerated in conductor 2 for clarity. Filling the interstices 23 and forming a layer on one side of the contacts 24 is a resilient conductive adhesive 22 which supports the contacts 24 and connects them, both mechanically and electrically, to a surrounding solid conductive sleeve 20. The adhesive 22 provides the necessary flexibility to the contacts 24 while simultaneously presenting a mechanically continuous interior conductive surface around the entire peripheral intersection with the tapered end 26 of the male half 8 of the connector. The adhesive 22 might advantageously be a conductive silicone adhesive. The end of the sleeve 20 forms a butt joint contact with a solid male conductor 28 thereby further insuring a good electrical connection between the connector halves and presenting a substantially mechanically continuous exterior surface for the entire center conductor 12. The out side diameter 32 of the center conductor 12, which is one of the critical dimensions of a coaxial connector, is not subject to change caused by connector wear from repeated insertions and disconnections because the exterior surface of the center conductor 12 does not contact any other part of the connector. All contact between the halves of the connector is in the protected interior.

The outer conductor of the female half 6 of the connector 101 includes outer spring contact 16 mounted in a recess 21 around the interior surface of a solid conductive sleeve 14. The spring contact 16 may advantageously be formed from a thin sleeve of conductive material as: shown in FIG. 3. The sleeve is longitudinally separated into a plurality of fingers 37 which are supported and joined on one end by a ring 36 or section of the thin sleeve which has not been separated. The ring 36 of contact 16 has a flaired edge or lip 52 which is inserted into a groove M around the interior periphery of sleeve M to hold the contact 16 in place. The fingers are bent in an appropriate configuration to fonn contact edges 38 which insure a good resilient contact. When the male sleeve 18 of the male half 8 of connector llllll is inserted into the contact 16, the edges 38 are compressed and caused to contact both the female sleeve M and the male sleeve 1b to insure a good electrical connection by the connector halves around the entire periphery of the connector. The end of the male sleeve 18 also forms a butt joint or connection with the female sleeve M at the rear of recess 21 to further insure a good electrical contact by the connector halves and to form a substantially mechani cally continuous interior surface for the outer conductor W.

The diameter 34 of the interior surface of the outer conductor is not subject to change caused by connector wear because all components subject to wear are on the exterior of this surface. As previously mentioned, diameter 32 is also not subject to change caused by connector wear. Thus, the ratio of inner diameter 34 of the outer conductor 10 to the outer diameter 32 of the inner conductor 12 is constant for the life of the connector. Consequently, the impedance of the connector remains constant.

A small gap 30 between the joined connector halves permits the use of larger tolerances on the lengths of the mating parts. The connector 101 as shown in FIG. 1 has very low RF leakage. The leakage may be reduced even further by installing a suitable compliant, conductive washer (not shown) in the gap 30.

FIGS. 4 and 5 show other designs for the contact 16 of the outer conductor 10. The design in FIG. 4 is similar to that in FIG. 3, except that the fingers 44 of the contact 40 have been shaped differently. Support ring 42 has a lip 43 for locking in groove 54 on the interior surface of sleeve 14. Fig. 5 shows a contact 46 having contact edges 50 in the form of a flexible corrugated sleeve which contact both the female sleeve 14 and the mating male sleeve 18. The corrugated sleeve is supported by ring 48 which has a lip 49 for locking in groove 54.

The connector 101 requires only a relatively small amount of expensive materials. The contacts 16 and 24 are the only elements in which the use of expensive materials might be justified as a matter of course. These contacts 16 and 24 might advantageously be made of gold-plated beryllium copper to obtain good electrical properties, spring properties, and wear characteristics. The remainder of the elements, such as sleeves l4 and 18, might advantageously be made of nickel-plated brass which is relatively inexpensive.

The connector 101, when equipped with a suitable locking device, is mechanically interchangeable with most presently used coaxial connectors of the type illustrated by the N series MIL C 390l2A. Because low-tolerance control of the dimensions of the elements is not required for good electrical contact, the connector is easy to connect and disconnect and thus may be used in a multiport-to-multiport application.

The particular embodiment disclosed herein is merely illustrative of the principles of the invention. Various modifications thereto may be made by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

l. A coaxial connector comprising, in combination:

a connector plug comprising a central pin of conductive material having a cylindrical portion and a tapered end portion projecting from the end of said cylindrical portion and forming a circumferential shoulder therewith, a tubular outer pin coaxially surrounding said central pin, said outer pin comprising first and second tubular portions, said second portion having an outer diameter smaller than the outer diameter of said first portion so that a circumferential shoulder is formed at the junction of said portions;

a receptacle for said plug comprising a central socket adapted to receive said tapered end portion of said central pin, said socket including a rigid sleeve of conductive material, a contact member including a plurality of contact fingers, and conductive resilient adhesive means for mounting said fingers around the inner surface of said rigid sleeve so that a flexible contact surface is provided for receiving said tapered end portion, said rigid sleeve having an outer diameter equal to the outer diameter of said cylindrical portion and forming a butt contact therewith so that said central pin and said central socket form an inner coaxial conductor having a smooth uniform and substantially continuous exterior surface when said plug and said receptacle are joined, an outer socket coaxially surrounding said central socket and adapted to receive said second portion of said outer pin of said plug,

said outer socket comprising a sleeve of conductive material including a recessed portion around the Interior surface thereof and a circumferential groove around one end of said recessed portion, said recessed portion forming a circumferential shoulder around the other end thereof, a contact member having a plurality of flexible fingers mounted within said recessed portion and having a lip on one end thereof inserted in said groove for holding said member in position, said recessed portion having an inner diameter greater than the outer diameter of said second portion of said outer pin so that said second portion is received therein to compress said contact member between said second portion and said recessed portion, the end of said second portion fonning a butt joint with said circumferential shoulder so that said outer pin and said outer socket from an outer coaxial conductor having a smooth uniform and substantially continuous inner surface when said plug and receptacle are joined, whereby the ratio of the inner diameter of said outer coaxial conductor to the outer diameter of said inner coaxial conductor is constant and independent of wear and distortion of all contact members.

A coaxial contact comprising, in combination:

a connector receptacle comprising inner and outer coaxial tubular members, said inner tubular member having a first flexible contact member mounted around the interior surface thereof, said first flexible contact member comprising contact fingers and conductive resilient adhesive means for mounting said contact fingers to said inner tubular member, said outer tubular member having a second flexible contact member mounted around the interior surface thereof within a recessed portion of said interior surface, said recessed portion forming a circumferential shoulder at one end thereof;

a conductor plug including inner and outer jack members,

said inner jack member comprising a conductor having a cylindrical portion and a tapered end portion extending from said cylindrical portion, said tapered end portion being adapted for insertion within said first flexible contact member to make contact therewith, said cylindrical portion forming a butt joint with said inner tubular member so that an inner coaxial conductor having a smooth uniform and substantially continuous outer surface is obtained, said outer jack member being adapted for insertion within said outer tubular member, said second contact member being compressed between said outer jack member and said outer tubular member, said outer jack member forming a butt joint with said circumferential shoulder so that an outer coaxial conductor having a smooth uniform and substantially continuous inner surface is obtained, whereby the ratio of the inner diameter of said outer coaxial conductor and the outer diameter of said inner coaxial conductor is constant and independent of wear and distortion of said contact members.

i I i t I! 

1. A coaxial connector comprising, in combination: a connector plug comprising a central pin of conductive material having a cylindrical portion and a tapered end portion projecting from the end of said cylindrical portion and forming a circumferential shoulder therewith, a tubular outer pin coaxially surrounding said central pin, said outer pin comprising first and second tubular portions, said second portion having an Outer diameter smaller than the outer diameter of said first portion so that a circumferential shoulder is formed at the junction of said portions; a receptacle for said plug comprising a central socket adapted to receive said tapered end portion of said central pin, said socket including a rigid sleeve of conductive material, a contact member including a plurality of contact fingers, and conductive resilient adhesive means for mounting said fingers around the inner surface of said rigid sleeve so that a flexible contact surface is provided for receiving said tapered end portion, said rigid sleeve having an outer diameter equal to the outer diameter of said cylindrical portion and forming a butt contact therewith so that said central pin and said central socket form an inner coaxial conductor having a smooth uniform and substantially continuous exterior surface when said plug and said receptacle are joined, an outer socket coaxially surrounding said central socket and adapted to receive said second portion of said outer pin of said plug, said outer socket comprising a sleeve of conductive material including a recessed portion around the interior surface thereof and a circumferential groove around one end of said recessed portion, said recessed portion forming a circumferential shoulder around the other end thereof, a contact member having a plurality of flexible fingers mounted within said recessed portion and having a lip on one end thereof inserted in said groove for holding said member in position, said recessed portion having an inner diameter greater than the outer diameter of said second portion of said outer pin so that said second portion is received therein to compress said contact member between said second portion and said recessed portion, the end of said second portion forming a butt joint with said circumferential shoulder so that said outer pin and said outer socket from an outer coaxial conductor having a smooth uniform and substantially continuous inner surface when said plug and receptacle are joined, whereby the ratio of the inner diameter of said outer coaxial conductor to the outer diameter of said inner coaxial conductor is constant and independent of wear and distortion of all contact members.
 2. A coaxial contact comprising, in combination: a connector receptacle comprising inner and outer coaxial tubular members, said inner tubular member having a first flexible contact member mounted around the interior surface thereof, said first flexible contact member comprising contact fingers and conductive resilient adhesive means for mounting said contact fingers to said inner tubular member, said outer tubular member having a second flexible contact member mounted around the interior surface thereof within a recessed portion of said interior surface, said recessed portion forming a circumferential shoulder at one end thereof; a conductor plug including inner and outer jack members, said inner jack member comprising a conductor having a cylindrical portion and a tapered end portion extending from said cylindrical portion, said tapered end portion being adapted for insertion within said first flexible contact member to make contact therewith, said cylindrical portion forming a butt joint with said inner tubular member so that an inner coaxial conductor having a smooth uniform and substantially continuous outer surface is obtained, said outer jack member being adapted for insertion within said outer tubular member, said second contact member being compressed between said outer jack member and said outer tubular member, said outer jack member forming a butt joint with said circumferential shoulder so that an outer coaxial conductor having a smooth uniform and substantially continuous inner surface is obtained, whereby the ratio of the inner diameter of said outer coaxial conductor and the outer diameter of said inner coaxial conductor is constant and independent of wear and distortion of said contact members. 